无取向硅钢中第二相的析出行为

Precipitation of Second Phase in Non-oriented Silicon Steel

使用扫描电镜(SEM)和能谱仪(EDS)等手段并结合热力学和动力学计算,研究了无取向硅钢900~1000℃常化处理过程第二相的析出行为。结果表明,无取向硅钢中的第二相主要为AlN和少量MnS。AlN和MnS在不同基体相(α相、γ相及(α+γ)两相)中有三种析出形核机制(均匀形核、晶界形核和位错形核),其临界形核半径(d*)都随常化温度的提高而增大。在同一温度下,相对于其他基体相AlN在(α+γ)两相区中晶界形核的临界形核功最小,相对形核率最大,因此以晶界形核为主;而MnS在α相中位错线上临界形核半径最小,相对形核率大,开始析出温度低,因此以位错形核为主。

The precipitation behavior of second phase in non-oriented silicon steel during normalization treatment at 900~1000℃was investigated by means of scanning electron microscope(SEM)observation and energy dispersive spectrometer(EDS),and thermodynamic and kinetic calculations.The result show that the second phases in non-oriented silicon steel are mainly AlN with a small amount of MnS.The critical nucleation radius(d*)of AlN and MnS particles increases with the increase of precipitation temperature for different matrix phases,namelyα-phase,γ-phase and(α+γ)two-phase respectively,which accord with three different precipitation nucleation mechanisms i.e.uniform nucleation,grain boundary nucleation and dislocation nucleation.By taking the second phase nucleation behavior at the same temperature as comparison,among others the critical nucleation work of grain boundary nucleation of AlN is the smallest,the relative nucleation rate is the largest,so grain boundary nucleation is easy to occur in(α+γ)two-phase area.Besides,the critical nucleation radius of MnS on the dislocation line is the smallest,the relative nucleation rate is large,and the initial precipitation temperature is low,therefore,the dislocation nucleation is dominated for MnS precipitates in theα-phase matrix.